Materials Data on NaSr3Be3B3O9F4 by Materials Project
NaSr3Be3B3O9F4 crystallizes in the trigonal R3m space group. The structure is three-dimensional. Na1+ is bonded in a distorted rectangular see-saw-like geometry to four F1- atoms. There are three shorter (2.25 Å) and one longer (2.42 Å) Na–F bond lengths. Sr2+ is bonded in a 7-coordinate geometry to six O2- and three equivalent F1- atoms. There are a spread of Sr–O bond distances ranging from 2.69–3.05 Å. There are one shorter (2.46 Å) and two longer (2.56 Å) Sr–F bond lengths. Be2+ is bonded to three O2- and one F1- atom to form corner-sharing BeO3F tetrahedra. There is one shorter (1.59 Å) and two longer (1.60 Å) Be–O bond length. The Be–F bond length is 1.70 Å. B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.38 Å) and one longer (1.40 Å) B–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Sr2+, one Be2+, and one B3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Sr2+, one Be2+, and one B3+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to one Na1+ and three equivalent Sr2+ atoms to form distorted FNaSr3 tetrahedra that share corners with four equivalent FNaSr3 tetrahedra, a cornercorner with one FNaBe3 trigonal pyramid, and edges with two equivalent FNaSr3 tetrahedra. In the second F1- site, F1- is bonded to one Na1+ and three equivalent Be2+ atoms to form distorted corner-sharing FNaBe3 trigonal pyramids.